patch 8.0.1468: illegal memory access in del_bytes()

Problem:    Illegal memory access in del_bytes().
Solution:   Check for negative byte count. (Christian Brabandt, closes #2466)
diff --git a/src/version.c b/src/version.c
index 767a348..e4a4b51 100644
--- a/src/version.c
+++ b/src/version.c
@@ -772,6 +772,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    1468,
+/**/
     1467,
 /**/
     1466,